1.) To identify, recruit, characterize clinically, and follow longitudinally until death patients with idiopathic Parkinson's Disease (PD) and healthy controls who consent to eventual autopsy, thereby providing material for the Neuropathology Core and teh neuropathologic studies in Projects #1-4 of the PD Research Center (PDRC). Clinical characterization will invole assessment of the motor, cognitive, and psychiatric features of PD. Comparable assessments will be conducted on controls. 2.) In conjunction with the Administrative Core of teh PDRC and the biostatistician, the Clinical Core will develop and maintain a computerized database of all clinical data obtained on participating subjects, and provide ongoing quality control and statistical support for studies in the Center gran using this information. These data will also be available to investigators with JHMI. 3.) To provide the fundamental infrastructure for a clinical research program on PD that facilitates independently funded clinical and clinical pathologica investigations of PD, and to coordinate the lingicudinal assessments by the Clinical Core with subject participation in these additional studies. 4.) To train physician-scientists in the clinical assessment and management of patients with PD and related disorders and the performance of clinical research on PD.